Verbindungen an der Zintl-Grenze: Darstellung und Kristallstruktur von Na17Ga29ln 12 und K17In41 / Compounds at the zintl border: preparation and crystal structure of Na17Ga29ln 12 and K17In41

Abstract

Na17Ga29ln12 (a = 2178.5(5) pm, Fd3m, Z = 8, R = 0.081) and K17In41 (a = 2424.1(5) pm, Fd3m, Z = 8, R = 0.060) have been prepared from the elements and characterized by single crystal X -ray methods. Na17Ga29ln12 is a ternary variant of K17In41. The crystal structure of Na17Ga29ln12 contains Ga12 icosahedra (In 12 icosahedra in K17In41) and truncated In12 tetrahedra which are four-capped and centred by additional Ga atoms (In atoms in K17In41). The packing of icosahedra and truncated tetrahedra leads to interpenetrating Samson polyhedra. The Ga12 icosahedra (In12 icosahedra in K17In41) take the Cu positions of the MgCu2 type, the In12 clusters take the positions of the Mg atoms of this structure type. The alkali atoms in Na17Ga29In12 and K17In41 occupy the deltahedral faces of the icosahedra and form pentagonal dodecahedra